EP3421834B1 - Method for measuring wear of the brake discs of an aircraft - Google Patents

Description

The invention relates to a method for measuring wear of the brake discs of an aircraft.

BACKGROUND OF THE INVENTION

Modern aircraft brakes comprise a stack of discs (also called a heat sink) which are pressed together by means of pistons or pushers to generate a braking moment to slow the wheel to which the brake is associated. The discs are likely to wear out each time you brake and it is important to know their state of wear to plan their replacement with a stack of discs of adequate thickness. In this regard, the brakes are generally equipped with at least one wear indicator which is slidably mounted on a fixed part (for example the hydraulic crown of the brake) and which is required to come into contact with the face of the facing discs. of the brake pistons, so that it moves in its housing as the discs wear. Its position is therefore indicative of the state of wear of the disk stack.

To give an order of magnitude, the heat sinks are typically changed after 2000 to 4000 landings, which depending on the rate of use of the aircraft, represents one year of operation of the aircraft. In this time, the disc stack has lost 5 to 6 centimeters of thickness.

The operators responsible for maintenance regularly check the position of the wear indicator (typically at a weekly frequency) to check the state of wear of the discs, and replace them with new discs if the wear indicator reaches a maximum wear position. It is an elementary, reliable process, but does not make it possible to precisely estimate the current wear of the discs of the inspected brake. This process makes any automated monitoring of brake disc wear on a given aircraft difficult.

To improve the monitoring of brakes in service, it was proposed in the document US2009/0205910 to replace this wear indicator with a wear sensor capable of generating at any time a signal representative of the state of wear of the discs. However, such a sensor requires expensive specific development. It must be very reliable, not break, not drift. The environmental conditions of its operation are severe: vibrations, carbon dust, spraying with liquids, high temperatures. In addition, all aircraft have several braked wheels, therefore several brakes, for example four (A320, B737), eight (A330, B787), twelve (B777), sixteen (B747 or A380) braked wheels, and it is important to distinguish all the wear signals coming back from the multiple brakes, to associate them with the correct heat sink. Finally, such a sensor involves a modification of the brakes in service, a modification of the electrical wiring reaching the level of the brakes, which generates significant requalification costs, and involves modification campaigns for aircraft in service.

The document EP 3 051 250 A1 describes a method for determining a length of a wear indicator of an aircraft brake.

OBJECT OF THE INVENTION

The invention aims to propose a method for measuring the wear of aircraft brake discs, allowing reliable monitoring of wear, but not requiring modification of the current brakes.

BRIEF DESCRIPTION OF THE INVENTION

With a view to achieving this goal, a method is proposed for measuring the wear of the discs of an aircraft brake provided with a wear indicator mounted movably on a fixed part of the brake and moving progressively. measurement of disc wear. The method of the invention comprises taking at least one photograph of the wear indicator, while the aircraft is stationary on the ground and analyzing the photograph to estimate a position of the wear indicator.

The analysis of each of the photographs can be done directly by the camera which was used to take the photograph. Alternatively, the photograph can be sent for storage and analysis to a remote receiver, for example an airline or brake manufacturer's maintenance server. In practice, the photograph can be taken by the operator using a simple smartphone.

By associating the estimate of wear with a number of flights carried out by the aircraft at the time of taking the image, it is then possible to monitor the wear of the discs during their lifespan and thus verify the proper functioning of the discs. brakes, or generate statistics on brake use. The number of flights carried out can be provided by the operator, or deduced from flight data provided by the company.

Preferably, the method comprises entering into the camera the identifier of the aircraft (for example its registration) and the position of the brake to be photographed. On the basis of this data, the method then comprises the step of generating a mask which is displayed on a display screen of the camera, so that the operator can make the mask and the image seen through the lens of the camera coincide. This shooting aid considerably facilitates the analysis of the photograph, since it is taken at a substantially identical shooting angle and distance each time.

BRIEF DESCRIPTION OF THE DRAWINGS

• La figure 1 est une vue en perspective d'un frein d'aéronef connu en soi, équipé d'un témoin d'usure ;
• La figure 2 est une vue d'un appareil de prise de vue utilisé par un opérateur pour la mise en œuvre du procédé de l'invention, en cours de prise de vue ;
• La figure 3 est une vue partielle du frein de la figure 1 au niveau du témoin d'usure.

The invention will be better understood in the light of the description which follows with reference to the figures of the appended drawings, among which:

• There figure 1 is a perspective view of an aircraft brake known per se, equipped with a wear indicator;
• There figure 2 is a view of a camera used by an operator for implementing the method of the invention, during photography;
• There Figure 3 is a partial view of the brake of the figure 1 at the wear indicator.

DETAILED DESCRIPTION OF THE INVENTION

As illustrated on the figure 1 , a typical aircraft brake 1 comprises a torque tube on which a stack of discs (or heat sink) 2 comprising stator discs 2A and rotor discs 2B is threaded to extend between a hydraulic crown 3 carrying pistons 4 and a back plate attached to the other end of the tube. The brake thus constituted is fitted onto the axle of an aircraft undercarriage which receives a wheel whose rim comprises bars for rotating the rotor disks 2B. Brake 1 is equipped with a wear indicator 6 (there are often two on one brake), here a simple metal rod slidably mounted on the hydraulic crown 3, and required to remain in contact with the stack of discs, so that the wear indicator recedes as the discs wear. The indicator can for example be attached to a thrust plate placed on the front of the heat sink 2, or be pushed back towards the first stator by a spring. All this is well known and is only recalled for illustration purposes.

• L'opérateur démarre une application embarquée dédiée à la mesure d'usure et implantée sur l'appareil de prise de vues;
• L'opérateur entre l'identifiant de l'aéronef (par exemple son immatriculation), et la position du frein sur l'aéronef dont il désire mesurer l'usure ;
• Comme illustré à la figure 2, l'application présente sur l'écran de l'appareil de prise de vues 8 un masque 10 spécifique au frein ainsi identifié, ici une série de contours en traits pointillés ;
• L'opérateur bouge l'appareil de prise de vue 8 pour le placer de sorte que le contour de la couronne hydraulique 3 et du témoin d'usure 6 tels que vus par l'objectif de l'appareil de prise de vue et affiché sur l'écran de visualisation de l'appareil coïncide avec les contours stylisés du masque 10 ;
• Une fois l'appareil de prise de vue placé correctement, l'opérateur prend la photographie, par exemple en appuyant sur le bouton virtuel 11 de l'écran. Le placement correct peut le cas échéant être confirmé par l'émission d'un signal sonore ou encore une mise en surbrillance des contours du masque 10. En variante, la photographie peut être déclenchée automatiquement dès qu'il est identifié que l'appareil de prise de vue est correctement placé ; - Après validation de la photographie, celle-ci est analysée pour estimer la position du témoin d'usure et donc l'usure des disques du puits de chaleur.

According to the invention, the maintenance operator who wishes to know the state of wear of the stack of discs approaches the brake concerned with a camera 8, here a simple smartphone. The procedure of the invention comprises the following steps:

• The operator starts an on-board application dedicated to wear measurement and installed on the camera;
• The operator enters the identifier of the aircraft (for example its registration), and the position of the brake on the aircraft whose wear he wishes to measure;
• As illustrated in figure 2 , the application presents on the screen of the camera 8 a mask 10 specific to the brake thus identified, here a series of contours in dotted lines;
• The operator moves the camera 8 to place it so that the outline of the hydraulic crown 3 and the wear indicator 6 as seen by the lens of the camera and displayed on the display screen of the device coincides with the stylized contours of the mask 10;
• Once the camera is placed correctly, the operator takes the photograph, for example by pressing the virtual button 11 on the screen. The correct placement can, if necessary, be confirmed by the emission of an audible signal or by highlighting the contours of the mask 10. Alternatively, photography can be triggered automatically as soon as it is identified that the shot is correctly placed; - After validation of the photograph, it is analyzed to estimate the position of the wear indicator and therefore the wear of the heat sink disks.

The analysis of the photograph is greatly facilitated by the fact that the shooting angle and the distance from the camera to the brake is identical from one photograph to another. Only the position of the wear indicator needs to be identified, in a substantially constant visual environment. Simple visual recognition algorithms can then be used to reliably determine the position of the wear indicator. It is then immediate to associate with this position a wear of the stack of disks 2. The analysis of the photograph can be carried out directly by the application embedded on the camera. Alternatively, the photograph can be automatically sent for analysis to a maintenance server, for example belonging to the airline or the brake manufacturer. The analysis of the photograph is then carried out remotely.

It is therefore possible to constitute a database associating, for each brake or heat sink, the identifier of the aircraft on which it is mounted, its position on the aircraft, the multiple photographs taken and the associated estimates of wear, dates, time and geolocation of the photographs, the number of flights carried out by the aircraft at the time of the photograph.

This database makes it possible to monitor the wear of each heat sink, to monitor the overall wear of the heat sinks of a given aircraft, or to establish wear statistics by aircraft, by line served, by fleet of a company... and makes it possible to program in advance a brake replacement action taking into account the foreseeable evolution of the wear of the heat sinks.

In practice, the database also contains the serial number of each of the heat sinks of each of the brakes so that the wear data can be associated with the corresponding heat sink.

The method of the invention therefore allows much richer processing of heat sink wear data, at the cost of developing a relatively simple application, without modification of existing brakes or development of an on-board wear sensor.

According to a particular aspect of the invention, and to facilitate the analysis of the photograph, the free end of the wear indicator is equipped with a visual marker that is easily identifiable and localizable, for example a sphere 9 visible on the Figure 3 . To improve its identification, the sphere 9 is preferably painted in a high contrast color, such as fluorescent orange. For to further facilitate the identification of the wear indicator on the photograph, the operator will be able to locally clean the crown which is generally painted white to increase the contrast between the crown and the wear indicator.

The invention is not limited to what has just been described, but on the contrary encompasses any variant falling within the scope defined by the claims.

In particular, although the method described includes the step of displaying a mask on the display screen to facilitate the positioning of the camera, we can do without this step if the analysis algorithm image is sufficiently sophisticated to identify the wear indicator and its position whatever the shooting angle and the distance of the camera from the brake concerned.

Likewise, although the method described includes the entry of an aircraft identifier, this data can be obtained by other means such as geolocation, or reception of an identification signal emitted by the aircraft himself.

Likewise, although the method described includes entering the position of the brake on the aircraft, this data can be obtained by other means. In particular, it is possible to ask the operator to respect a sequence of photographs of the brakes, so as to systematically identify which brake is being photographed. For example, on an aircraft with four brakes such as A320 or B737, the operator will be asked to photograph the brakes in the order of their numbering (brakes from 1 to 4, starting from the left outer brake to the right outer brake), taking care to let him know if he is changing brakes before each new photograph.

Claims (7)

1. A method of measuring disk (2) wear in an aircraft brake (1) having a wear indicator (6) that is movably mounted on a stationary portion of the brake (1) and that moves progressively with increasing disk wear, the method being characterized in that it comprises using a picture-taking appliance (8) to take at least one photograph of the wear indicator while the aircraft is stationary on the ground, and analyzing the photograph in order to only estimate the position of the wear indicator and deduce therefrom the wear of the disks.
2. The method according to claim 1, including inputting an identifier of the aircraft, inputting the position of the brake in question, and presenting a mask (10) on a display screen of the picture-taking appliance, which mask is specific for providing assistance in positioning the picture-taking appliance correctly relative to the brake in question by bringing the mask into alignment with an outline of a portion of the brake and/or of the wear indicator as visible on the display screen, prior to taking the photograph.
3. The method according to claim 1, wherein the photograph is analyzed by an analysis algorithm installed in the picture-taking appliance.
4. The method according to claim 1, wherein the estimated position of the wear indicator is stored in a database in association with an identifier of the aircraft and with the position of the brake on the aircraft.
5. The method according to claim 2, wherein the estimated position of the wear indicator is associated with at least one of the following data items:

   - the date and time of the photograph;

   - the geolocation of the photograph; and

   - the number of flights taken by the aircraft at the time the photograph is taken.
6. The method according to claim 1, wherein the estimated position of the wear indicator is sent to a remote server for storage and statistical analysis.
7. The method according to claim 1, wherein the wear indicator is provided with a visual marker (9) that is identifiable in the photograph.

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